Deuterium isotope effects in the solvolysis of benzal chlorides. 5. Salt effects and solvent isotope effects

1981 ◽  
Vol 103 (8) ◽  
pp. 1982-1984 ◽  
Author(s):  
V. P. Vitullo ◽  
F. P. Wilgis
Keyword(s):  
Isotope Effects ◽  
Salt Effects ◽  
Deuterium Isotope Effects ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

scholarly journals Deuterium Isotope Effects on Acid-Base Equilibrium of Organic Compounds

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7687
Author(s):  
Meiyi Liu ◽  
Jiali Gao
Keyword(s):  
Free Energy ◽  
Isotope Effects ◽  
Linear Free Energy Relationship ◽  
Acid Base ◽  
Exchange Effect ◽  
Linear Free Energy ◽  
Acid Base Equilibrium ◽  
Deuterium Isotope Effects ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

Deuterium isotope effects on acid–base equilibrium have been investigated using a combined path integral and free-energy perturbation simulation method. To understand the origin of the linear free-energy relationship of ΔpKa=pKaD2O−pKaH2O versus pKaH2O, we examined two theoretical models for computing the deuterium isotope effects. In Model 1, only the intrinsic isotope exchange effect of the acid itself in water was included by replacing the titratable protons with deuterons. Here, the dominant contribution is due to the difference in zero-point energy between the two isotopologues. In Model 2, the medium isotope effects are considered, in which the free energy change as a result of replacing H2O by D2O in solute–solvent hydrogen-bonding complexes is determined. Although the average ΔpKa change from Model 1 was found to be in reasonable agreement with the experimental average result, the pKaH2O dependence of the solvent isotope effects is absent. A linear free-energy relationship is obtained by including the medium effect in Model 2, and the main factor is due to solvent isotope effects in the anion–water complexes. The present study highlights the significant roles of both the intrinsic isotope exchange effect and the medium solvent isotope effect.

Kinetic deuterium isotope effects and kinetic solvent isotope effects for the solvolyses in water and in water + acetonitrile mixtures related to a series of substituted benzyl nitrates

1980 ◽  
Vol 58 (20) ◽  
pp. 2142-2145 ◽  
Author(s):  
Mohammed Ahsan ◽  
Ross Elmore Robertson ◽  
Michael Jesse Blandamer ◽  
John Marshall William Scott
Keyword(s):  
Aqueous Solution ◽  
Benzene Ring ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Bond Breaking ◽  
Relative Importance ◽  
Stage Process ◽  
Deuterium Isotope Effects ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

In aqueous solution, the α-deuterium isotope effects in the solvolyses of benzyl nitrates derivatives depend on the nature of the substituent in the benzene ring. In addition, the isotope effect for some derivatives depends on mole fraction of added acetonitrile while for others the isotope effect is insensitive to solvent composition. However, the kinetic solvent isotope effects for para-methyl and meta-trifluoromethyl derivatives remain unchanged when acetonitrile is added. These observations are accounted for in terms of a model which describes the solvolytic reaction as a two-stage process and contrasts the relative importance of bond-making and bond-breaking.

Pseudo-thermodynamic Parameters and Isotope Effects for Hydrolysis of a Series of Benzyl Chlorides in Water

1973 ◽  
Vol 51 (17) ◽  
pp. 2958-2962 ◽  
Author(s):  
K. M. Koshy ◽  
R. E. Robertson ◽  
W. M. J. Strachan
Keyword(s):  
Temperature Coefficient ◽  
Isotope Effects ◽  
Probable Mechanism ◽  
Benzyl Chlorides ◽  
Enthalpy Of Activation ◽  
Mechanism Of Hydrolysis ◽  
Deuterium Isotope Effects ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Solvent Isotope Effects

The temperature coefficient of the enthalpy of activation (ΔCp≠) for the hydrolysis of p-methyl, p-chloro and p-nitro benzyl chlorides have been determined, as well as α-deuterium isotope effects and kinetic solvent isotope effects. These results are discussed in terms of probable mechanism of hydrolysis in water.

scholarly journals Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions

2021 ◽  
Vol 22 (14) ◽  
pp. 7394
Author(s):  
Kyoung Ho Park ◽  
Mi Hye Seong ◽  
Jin Burm Kyong ◽  
Dennis N. Kevill
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Carbonyl Sulfide ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Reaction Channels ◽  
Decomposition Pathway ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.

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